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127 lines
4.7 KiB
127 lines
4.7 KiB
/**************************************************************************** |
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* binfmt/symtab_findorderedbyvalue.c |
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* |
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* Copyright (C) 2009 Gregory Nutt. All rights reserved. |
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* Author: Gregory Nutt <gnutt@nuttx.org> |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in |
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* the documentation and/or other materials provided with the |
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* distribution. |
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* 3. Neither the name NuttX nor the names of its contributors may be |
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* used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS |
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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* POSSIBILITY OF SUCH DAMAGE. |
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* |
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****************************************************************************/ |
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/**************************************************************************** |
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* Included Files |
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****************************************************************************/ |
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#include <nuttx/config.h> |
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#include <stddef.h> |
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#include <debug.h> |
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#include <assert.h> |
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#include <errno.h> |
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#include <nuttx/binfmt/symtab.h> |
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/**************************************************************************** |
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* Pre-processor Definitions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Function Prototypes |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Data |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Functions |
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****************************************************************************/ |
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/*********************************************************************** |
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* Public Functions |
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***********************************************************************/ |
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/**************************************************************************** |
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* Name: symtab_findorderedbyvalue |
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* |
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* Description: |
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* Find the symbol in the symbol table whose value closest (but not greater |
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* than), the provided value. This version assumes that table is ordered |
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* with respect to symbol name. |
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* |
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* Returned Value: |
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* A reference to the symbol table entry if an entry with the matching |
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* name is found; NULL is returned if the entry is not found. |
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* |
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****************************************************************************/ |
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FAR const struct symtab_s * |
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symtab_findorderedbyvalue(FAR const struct symtab_s *symtab, |
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FAR void *value, int nsyms) |
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{ |
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int low = 0; |
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int high = nsyms -1; |
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int mid; |
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/* Loop until the range has been isolated to a single symbol table |
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* entry that may or may not match the search name. |
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*/ |
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DEBUGASSERT(symtab != NULL); |
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while (low < high) |
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{ |
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/* Compare the name to the one in the middle. (or just below |
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* the middle in the case where one is even and one is odd). |
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*/ |
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mid = (low + high) >> 1; |
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if ( value < symtab[mid].sym_value) |
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{ |
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high = mid - 1; |
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} |
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else if (value > symtab[mid].sym_value) |
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{ |
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low = mid + 1; |
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} |
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else /* if (value == symtab[mid].sym_value) */ |
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{ |
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return &symtab[mid]; |
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} |
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} |
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/* low == high... One final check. We might not have actually tested |
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* the final symtab[] name. |
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* |
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* Example: Only the last pass through loop, suppose low = 1, high = 2, |
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* mid = 1, and symtab[high].sym_name == name. Then we would get here with |
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* low = 2, high = 2, but symtab[2].sym_name was never tested. |
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*/ |
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return value == symtab[low].sym_value ? &symtab[low] : NULL; |
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} |
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